$A$ refrigerator of coefficient of performance $5$ that extracts heat from the cooling compartment at the rate of $250 \ J$ per cycle is placed in a room. The heat released per cycle to the room by the refrigerator is (in $J$)

An ideal heat engine has an efficiency $\eta$. The coefficient of performance of the engine when driven backward will be

$A$ household refrigerator with a coefficient of performance $1.2$ removes heat from the refrigerated space at the rate of $60 \ kJ/min$. What would be the cost of running this fridge for one month $(30 \ days)$, assuming it is used for $4 \ hours$ each day and the cost of one electrical unit is $6 \ Rs.$?

The freezing compartment of a refrigerator is at $0^{\circ} C$ and the room temperature is $27.3^{\circ} C$. Calculate the work done by the refrigerator to freeze $1 \ g$ of water at $0^{\circ} C$. (Given: $L_{\text{ice}} = 80 \ cal \ g^{-1}$) (in $J$)

$A$ Carnot heat engine has an efficiency of $10 \%$. If the same engine is worked backward to obtain a refrigerator,then the coefficient of performance of the refrigerator is

Explain the working of refrigerators/heat pumps and their coefficient of performance.